We report the first six-dimensional quantum dynamical calculations of dissociative adsorption and associative desorption. Using a potential energy surface obtained by density functional theory calculations, we show that the increase of the sticking probability with decreasing kinetic energy at low kinetic energies in the system ${\mathrm{H}}_2/\mathrm{Pd}\left(100\right)$, which is usually attributed to the existence of a molecular adsorption state, is due to dynamical steering. In addition, we examine the influence of rotational motion and orientation of the hydrogen molecule on adsorption and desorption.

• Received 8 June 1995

DOI:https://doi.org/10.1103/PhysRevLett.75.2718